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RPi + OSMC Do I need to ground my APA102 lights in top left corner if I already grounded at bottom right corner

Discussion in 'Hardware Support' started by osorocks, 12 February 2019.

  1. osorocks

    osorocks New Member

    Messages:
    12
    Hardware:
    RPi3
    My Pi and Ambilight set up is finished, I got the rainbow swirl and everything.

    However my lights are flickering a bit sometimes.

    I used 158 APA102 lights for my tv (10 amps), for a length of 19 feet (82 inch tv). I used 17 awg primary wire (IS PRIMARY WIRE OK? it said on packaging for automotive use)

    Currently I have the beginning and end strip's GND and 5V (all at the BOTTOM RIGHT) linked to a terminal strip and then linked to the 5V 15 A power supply.

    I figured since there are 9 feet of LED STRIPS going clockwise from BOTTOM RIGHT and counterclockwise from BOTTOM RIGHT, that I would need to wire the 5V from led at TOP LEFT to the positive power supply and GND to the negative power supply terminal strip.

    I still have one more question before I try this.Since at the BOTTOM RIGHT I have a male to female connected to the gpio pin 6 for grounding, will I also have to ground the TOP LEFT corner? Or is it like DI/CI CO/DO where I only need to have the signal go one direction.

    My main questions are underlined.

    In the video. white circle is BOTTOM RIGHT and yellow circle is TOP LEFT (ssorry for mixmatching)
    You can see flicker near the white circle in this video
    https://vimeo.com/user95009912/review/316703000/59e07d3880
     
  2. Akriss

    Akriss Active Member

    Messages:
    450
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Wire is usually universal, the gauge is what matters. automotive wire is usually stranded wire as opposed to solid wire. stranded wire is flexible, solid wire not so much. In short it's ok.

    No, one ground wire is fine. Be sure that it's a good connection, loose ground (or any) wire can cause flicker.

    Some things come to mind in troubleshooting:
    Very long runs of wire between the led strip and the driver can act as a antenna and pick up stray signals that interfere with the led signal.
    Most micro controllers output 3.3v signals. The led strip are expecting a signal closer to 5v. And if using long runs of wire. Long wire add resistance and a subsequent voltage drop to the signal. A level shifter can be used to bump up the 3.3v signal to 5v.
    Having a strong signal to the leds can overcome interference.
    Lots of good posts on this forum on how to hook up a level shifter. I prefer 74AHCT125 level shifter.

    Hope its of help.
     
  3. osorocks

    osorocks New Member

    Messages:
    12
    Hardware:
    RPi3
    Can you link me a guide to installing a level shifter with raspberry pi and apa102?
     
  4. Akriss

    Akriss Active Member

    Messages:
    450
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    A very good guide Is Adfruits guide HERE.

    This guide is for different leds. But has good info. Here


    Hope it helps.
     
    Last edited: 12 February 2019
  5. osorocks

    osorocks New Member

    Messages:
    12
    Hardware:
    RPi3
    I am not quite sure I understand on the guides.

    So for my Rpi 3 and apa102 , I need to "level shift" gpio pins into CI/CO,DI/DO. When you are referring to signals, is it the signals that communicate what color each led turns?

    Do I still need to run another wire across the tv for 5v and gnd?

    I saw I needed a breadboard, is there a specific one i need?
     
  6. Akriss

    Akriss Active Member

    Messages:
    450
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Yes.

    Here it a picture I came upon that should help.
    raspberry_pi_power-2-batts.png
    The battery can be seen as any power supply.

    No, just make sure it has a pitch (hole spacing distance) of 0.1, most are.

    A good post is https://hyperion-project.org/threads/level-shifter.623/ for good info.

    A photo of one I cobbled together.
    [​IMG]

    Hope its of help.
     
    Last edited: 13 February 2019 at 23:05